STUDENT ABSTRACTS
Abundance Analysis and Modeling of Five Planetary
Nebulae
- James A. Bates
The spectra of five planetary nebulae
(PNe), J900, NGC 3242, NGC 2242, NGC 40, and IC 418, were reduced and analyzed
to determine abundances of helium, oxygen, carbon, nitrogen, neon, and sulfur.
These abundances, made with a five level electron balancing program, were used
as inputs for a modeling program. This approach takes the limited data from a
spectrum and interprets them with the help of a full photoionization model.
This work is a part of a project to study the abundances of 75 planetary
nebulae. The information in this homogeneous database can be used to compare
nucleosynthesis theories with observations, and can also be used to assess the
role PNe play in the chemical evolution of the galaxy.
High-Frequency Waves in the Solar Corona at the 1998 Total Eclipse
Implications for the Coronal Heating Problem
- Timothy H. McConnochie
We observed the total eclipse
of February 26, 1998, from the vicinity of Nord, Aruba, in order to search for
evidence of high-frequency waves in the solar corona. Images of the coronal
green line and of a reference spectral region in the coronal continuum were
acquired at a rate of 10 frames per second. Our Princeton Instruments CCD
camera was used in frame-transfer mode and was mounted on a 36 cm Celestron
Schmidt-Cassegrain telescope. Several theories of coronal heating rely on
high-frequency magnetohydrodynamic waves to transfer the necessary energy. We
hope to constrain theories of coronal heating by either detecting or ruling out
the presence of coronal oscillations produced by these waves. Preliminary
analysis of the 1998 data indicates that we should be able to either rule out
or detect coronal oscillations with normalized amplitudes greater than 1.5%.
No oscillations with amplitudes this large have yet been identified, although
coronal oscillations with normalized amplitudes of 0.8% do seem to be present
in two different locations. The frequencies of these apparent oscillations are
3.77 and 4.82 hertz respectively, but more rigorous statistical analyses are
required to determine if detections with amplitudes this far below our
conservative estimate of 1.5% can be considered real.
Inositolphosphorylceramide Synthesis in Plants: Characterization of
a Novel Enzyme Involved in Plant Sphingolipid
Metabolism
- Pamela E. Bromley
Iinositolphosphorylceramides (IPC)
are a class of sphingolipids present in plants, fungi, and protozoa. The
activity of IPX synthase, the enzyme catalyzing the first step in the synthesis
of complex inositolphosphorylceramides, has been characterized in a plant
system. This work represents the first detailed characterization of the enzyme
in any system, plant or fungal. IPC synthase catalyses the following reaction:
phosphatidylinositol + ceramide -> inositolphosphorylceramide +
diacylglycerol
Enzyme activity in a microsomal membrane faction from bean hypocotyls was
assayed by monitoring the incorporation of [3H]IPC and/or
fluorescent IPC. The apparent Km for PI was approximately 43
µM. The enzyme exhibited a relatively strong preference for ceramides
with d18:1 long chain bases and C18 and C24 non-hydroxy fatty acids, with
optimal activity at a substrate concentration of 0.27 nM. The pH optimum was
7.8, and the temperature optimum was 27.5ûC. Previously, IPC had only
been reported in a few important agricultural plants. Significantly, enzyme
activity was observed in a variety of different plants and tissues, lending
support to the notion that IPC are widespread if not ubiquitous in plants. A
known inhibitor of IPC synthase in fungi, aureobasidin A (AbA), was found to be
a potent inhibitor of IPC synthase in plants, with 50% inhibition at just 0.8
nM, indicating that AbA is a potential broad spectrum fungicide and herbicide.
Genetic, Molecular, and Cellular Studies of the CDC14
Pathway in Saccharomyces cerevisiae
- Meghan Byrne
CDC14 is an essential gene in the
budding yeast, Saccharomyces cerevisiae. This gene encodes a 62kD protein
containing the active site motif and in vitro activity of a
dual-specificity phosphatase (Taylor et al.. 1997). Mutations of
CDC14 are temperature sensitive, causing the cell cycle to arrest at
late anaphase/early telophase at the restrictive temperature (34-37ûC).
What proteins Cdc14p interacts with and how the CDC14 pathway controls
exit from mitosis are unknown. In this study, three lines of inquiry were
pursued to elucidate the CDC14 pathway. First, suppressor analysis was
performed to identify genes encoding proteins that suppress the temperature
sensitivity of cdc14 mutants and that potentially interact with Cdc14p.
Suppressor analysis was performed using cdc14--1 and cdc14-2
mutants, and both dominant and recessive suppressors were analyzed. Secondly,
a plasmid was created to clone the cdc14 mutant alleles for
characterization and nucleotide sequencing. The plasmid was created from the
pJWc100 plasmid, which has a pRS316 backbone and a CDC14 insert, using
site-directed mutagenesis to incorporate unique restriction sites at both ends
of the CDC14 open reading frame. These restriction sites will allow the
open reading frame to be excised and the mutant alleles to be rescued via gap
repair. Thirdly, bud-scar patterns in cdc14, sfp1-1, and
sfp1-2 mutants were analyzed. The sfp1 mutations were first
isolated as suppressors of cdc14's temperature-sensitivity phenotype
(Schilling 1995). The bud-scar pattern analysis revealed that, compared to
wild-type bud-scar patterns, cdc14 mutants grown at 25ûC exhibit
normal patterns, whereas sfp1-1 and sfp1-2 mutants exhibit a
high frequency of abnormal patterns of bud-site selection.
Methods to Uncover the Transmission of Birdsong in a Population of
House Finches, Carpodacus mexicanus
- Matthew A. Garland
Birdsong, as a learned trait, is
analogous to human speech, and because of its similarities has been well
studied in the past. However, it has been difficult to separate the
environmental component of learned song from any genetic component. A set of
methods, which will enable better understanding of the differences in the
biological transfer of birdsong, were devised and refined. These methods,
performed on the house finch, Carpodacus mexicanus, and the zebra finch,
taeniopygia guttata, have been divided into three distinct steps: capturing
and extracting blood from birds, extracting DNA from bird blood, and performing
RAPD-PCR (randomly amplified polymorphic DNA-polymerase chain reaction), using
the extracted genomic DNA as a template. The goal of the methods is to use
RAPD-PCR polymorphism data to construct a tree diagramming the relatedness of
the local populations of house finches; once this is accomplished, changes in
song characteristics can be mapped through the population, hopefully shedding
light on how and why birdsong changes in a population, and how song is related
to genetic factors.
Creation of an Antibody to and Characterization of the AAR1 Protein
in Arabidopsis thaliana
- Mary A. Gehring
Lateral root formation is known to be
induced by the plant hormone auxin. It is unknown, however, how auxin leads to
this morphological change. Previously, it was determined that an Arabidopsis
thaliana gene Arabidopsis Auxin Regulated 1 (AAR1) was expressed in root tissue
after auxin induction.
In this project, an antibody was made against the protein encoded by the early
auxin response gene. The antibody was used to detect AAR1 on Western Blots of
wild type Arabidopsis thaliana (Columbia ecotype) shoots and roots and in
transgenic arabidopsis plants which constitutively express the AAR1 gene. It
was expected that auxin application would cause an AAR1 protein increase in
wild type plants. Protein increase after auxin treatment was never detected in
shoots or roots, though higher levels of mRNA in transgenic plants produced
correspondingly higher AAR1 protein levels. It was also shown that AAR1 was
generally more abundant in wild type roots than shoots.
Characterization of Transgenic Plants that Overexpress
AAR1
- Arminda L. Gensler
Plants synthesize hormones that
travel throughout the organism and act as signaling molecules to cue
developmental processes. However, little definite is known about the exact
mechanisms of the plant hormone auxins action and auxin signal transduction.
This thesis attempts to further characterize the functional role of the novel
primary auxin response gene AAR1 in Arabidopsis thaliana. Transgenic strains
containing the AAR1 cDNA insert behind the constitutive 35S CaMV5 promotor show
increased accumulation of AAR1 mRNA relative to wt. These strains can be
ranked as followings according to relative increases in mRNA accumulation: wt,
C1K4, B1C2, C1C3, C1B6, B1B1. Transgenic plants that overexpress AAR1 mRNA and
protein do not appear to have a phenotype different from wt. This suggests
that the AAR1 gene product, by itself, does not play a critical role in plant
development. Transgenic plants that possess increased levels of AAR1 mRNA and
protein do not have increased accumulation of RPñ16 mRNA. RPL16 is a
secondary auxin response gene. This lack of induction suggests that AAR1,
alone, does not play a regulatory role in the auxin signal transduction pathway
for RPL16. The level of AAR1 mRNA accumulation in wt plants responds to
stimuli other than auxin. Heat shock causes a dramatic reduction in AAR1 mRNA
accumulation; cadmium chloride addition results in a moderate reduction of AAR1
mRNA accumulation. A complete sequencing of the AAR1 gene, including its
promotor region, would allow us to understand how it is regulated; thus, we
could potentially gain further insight into the function of this gene.
Early-Induced Puberty: Effects on Song Leaning in the Zebra
Finch
- Deborah A. Hirschmann
Unlike many other bird species,
male zebra finches are close-ended learners. Males acquire their song in
chunks from one or more song tutors (Williams & Staples, 1992), eventually
fixing syllables in a permanent order which they will sing in a stereotyped
manner for the rest of their lives. This song crystallization, occurring
between 70 and 90 days of age, marks the close of the critical period for song
acquisition (Immelman, 1969). Many lines of evidence suggest a role for
testosterone (T) in song crystallization. For example, the first major
testosterone surge in zebra finch males occurs around day 75, marking the onset
of both puberty and song stereotype (Prove, 1983). Furthermore, castrated
zebra finches add syllables to their songs well after song acquisition is
purportedly complete (Arnold, 1975), and males treated with testosterone early
in life produce prematurely crystallized songs (Korsia & Bottjer, 1991).
It thus appears that high plasma testosterone levels may close sensitive
periods for learning.
This study explored, through the administration of testosterone implants at 60
days, whether prematurely inducing puberty in male zebra finches limits their
critical period for song acquisition. It also attempted to further elucidate,
through the joint administration of testosterone and the T-antagonist
flutamide, the specific pathways by which testosterone influences song learning
and neural plasticity. The songs of treated birds differed from those of
controls in several respects. Birds treated with testosterone and flutamide
(TF) exhibited more changes in their song than did finches in the T-only or
control groups. When compared to controls, T-treated birds also appeared to
alter their syllables earlier and TF birds later in song development.
Intriguingly, birds added call-like and complex syllable types in the same
proportions as found in their original songs. Control birds appeared to
stabilize the identify of dominant song types around 90 days, while those of
treated birds remained more variable. Finally, TF birds tended to copy a lower
proportion of syllables from their tutors than did either T or control birds.
In conclusion, the present study suggests that while the administration of
exogenous testosterone at 60 days may induce early crystallization of song in
male zebra finches, decreasing the effects of androgenic exposure, through the
joint administration of testosterone and the anti-androgen flutamide, appears
to enhance neural plasticity and prolong critical periods for learning.
The Effect of Dispersal Mechanism on the Recolonization of Spring
Ephemeral Species from Primary to Secondary Woodlots
- Jody Knight
The history of Williamstown is one of
fluctuations in the extent of forest cover. Large chunks of forest were at one
time cleared for use as farmland and then allowed to regrow. This clearing of
the land has had a lasting impact on the forest flora, especially the
herbaceous layer, which takes much longer to return to forests than do tree
species. Spring ephemeral species, a major component of the herbaceous layer,
are hypothesized to work as a springtime "vernal dam," holding in the system
nutrients that might otherwise be lost due to leaching. The dispersal
mechanisms of spring ephemerals affects the way that these species recolonize
secondary forest (forest that has been cleared and then allowed to regrow) from
primary forest (forest that has never been cleared). Wind and vertebrate
dispersed species disperse at a higher rate than do ant dispersed species. Ant
dispersed species, on the other hand, once established tend to form a more
regular cover than do wind and vertebrate dispersed species. Other factors,
such as canopy composition, topography, and soil conditions, also appear to
affect the recolonization by spring ephemerals.
Genetic Variation for Plasticity in a Natural Population of the
Chorus Frog (Pseudacris triseriata)
- Carolyn McBride
Examining the potential for natural
selection on phenotypic plasticity is crucial to the study of evolution in
heterogeneous environments. It is therefore important to measure the
heritability of plastic responses within natural populations. Along the rocky
shore of North Government Island, Isle Royale National Park, MI, the chorus
frog (Pseudacris triseriata) breeds in small temporary pools. Pseudacris
tadpoles developing in pools with their main predator, the dragonfly nymph
(Aeshna juncea), develop larger tail fins than tadpoles developing in pools
without dragonflies. In this study, I tested for broad-sense heritability in
this plastic response by carrying out an experiment employing a split brood
full-sib design. I partitioned full-sibling tadpole families (sibships) among
natural pools containing either caged dragonflies (unable to kill experimental
tadpoles) or empty cages. By using RAPD-PCR based molecular markers to assign
experimental tadpoles to known sibships at the end of the experiment, I was
able to begin the predator and non-predator treatments as soon as the tadpoles
hatched, rather than waiting until they developed unique tail spot pigmentation
patterns by which to identify them. I monitored the morphology of experimental
tadpoles over the course of 25 days and described the plastic response of each
sibship as the set of phenotypes its members produced across the two
environments (reaction norm). I detected significant variability among
sibships in the mean (and possibly slope) of reaction norms for tail shape
indicating broad-sense heritability and a continued potential for the evolution
of tail phenotypes within this population.
Breeding System and Small-Scale Population Genetic Structure of
Sagina Nodosa (Caryophyllaceae), Isle Royale, Michigan
- Benjamin R. Montgomery
Loss of genetic diversity and
resulting inbreeding depression may affect the success of rare plant
populations. At the northeast tip of Isle Royale, Michigan, a community of
rare arctic plants has persisted for the last 10,000 years, and the populations
may be small enough to experience a substantial degree of inbreeding
depression. We investigate the partitioning of genetic diversity among one
island population of Sagina nodosa, an arctic-disjunct plant. We use the
technique of RAPD-PCR to detect genetic diversity among individual plants from
North Government Island, and we use several statistical tests, including
analysis of molecular variance (AMOVA) to determine whether diversity if
non-randomly distributed throughout the population. Our results indicate that
the population is highly structured among the sub-populations (p<0.01), and
among cracks in rocks within the sub-populations examined (p<0.1).
Furthermore, linear distance among sub-populations is not correlated to genetic
variation among sub-populations, which suggests that when gene flow does occur
between sub-populations, it may bypass intermediate sub-populations. Finally,
we determine that S. nodosa is fully self-compatible, which indicates that
sub-populations may be founded by as little as one individual plant. Overall,
these results suggest that a substantial amount of genetic variation occurs
between sub-populations of S. nodosa, suggesting that conservation efforts
should emphasize the maintenance of all sub-populations rather than only the
most successful ones.
Language and Brain: Effects of Arterial Occlusion (Stroke) on Human
Brain Morphometry and Specific Language Abilities
- Nedim T. Sahin
Language task localization in the human
brain was investigated using a lesion-study approach. MRI-based volumetric
lesion quantification and subsequent mapping in 21 adult stroke patients
revealed three patterns indicative of Middle Cerebral Artery perfusion fields.
Psycholinguistic aphasiological examination revealed that language deficits
could be broken down into discreet subunits, according to hierarchical models
of language processing. Correlational analysis showed that lesions in chosen
anatomic areas accounted for much variance in some language scores, tentatively
ratifying localizationist models; and further indicated a region in the
inferior temporal lobe to be strongly predictive of deficits on many tasks.
This study would be a fitting pilot for future research (including functional
studies) and the results are tentative. Nonetheless, the results suggest that
core language functions may be subserved by regions external to the classic
perisylvian language areas.
The study was carried out at Massachusetts General Hospital under the
supervision of Dr. Verne S. Caviness, Jr., who performed the original
morphometric analysis, and Dr. David N. Caplan, who performed the linguistic
assessment. My role has been to map the lesions, assess lesion patterns
(Sahin, et al., 1998), and perform correlational analyses to assess specific
language task localization.
Population Structure and Gene Flow in Chorus Frog Tadpoles
(Pseudacris triseriata) on North Government Island, Isle Royale National
Park
- Joshua A. Shapiro
This study examines the interactions
f gene flow and selection in structuring a population of chorus frog tadpoles
(Pseudacris triseriata) on North Government Island, Isle Royale National Park.
The island was mapped and characterized in detail, with particular reference to
the interactions between the tadpoles and their main predator, dragonfly
nymphs. Tadpoles from different regions of the island were raised in a natural
environment to discern genetic differences in morphology and RAPD-PCR was used
to analyze differences in neutral genetic markers among tadpoles.
Tadpoles from the northeast end of the island tended to have larger tailfins
relative to their body size, which corresponded to the fact that there was a
greater amount of interaction between the tadpoles and dragonfly nymphs at that
end of the island. There was not, however, any significant differentiation in
the RAPD markers between the tadpoles at the northeast end of the island and
those at the southwest end. There was a positive correlation between the
physical distance between the pools from which tadpoles originate and the
genetic distance between the tadpoles from those pools, but only at a small
scale (<50m).
These data suggest that the level of gene flow in the population of tadpoles on
North Government Island is somewhat restricted, likely by the fact that adult
frogs return to the region near the pool in which they metamorphosed to mate.
This restriction in gene flow is not enough to cause large scale
differentiation between the ends of the island, as evidenced by the RAPD data,
but it is sufficient to create a gradient in the expression of genes such as
tailfin height, which are targets of selection.
Elucidating the Genetic Mechanisms of Muscle Fiber-Type Diversity:
An In Vivo Transcriptional Analysis of the Myosin Heavy Chain Type IIB
Promoter
- Emily C. Snyder
The aim of this project was to
identify and characterize the fast muscle fiber-type specific element(s) of the
myosin heavy chain type IIB (IIB-MyHC expression. Numerous deletion constructs
that targeted evolutionarily conserved motifs were generated in the context of
the proximal 300 bp. In vivo activity of each promoter deletion construct was
determined in the fast-twitch tibialis anterior (TA) muscle and the slow twitch
soleus muscle of the rat hindlimb by the technique of somatic gene transfer.
Transcriptional activity of each construct in myotube culture was also
determined in a cell culture transfection study. Deletion of the two distal
AT-rich regions, mAT3 and mAT2, resulted in a marked decrease of activity in
the soleus and TA, suggesting that these elements are required for high levels
of activity of the promoter. Deletion of these two elements distal AT-rich
regions caused a parallel decrease of activity in myotube culture. The mAT3
region seems to be involved in non-fiber-type specific regulation of the
promoter. However, because deletion of the mAT2 region caused changes in the
ratio of soleus:TA expression, this element may have a partial role in
conferring fast-twitch fiber specificity to the IIB-MyHC promoter. Deletion of
a third proximal AT-rich region, AT1, resulted in a significant increase in
activity in both the TA and the soleus muscles, indicating that it is a
non-fiber-type specific transcriptional repressor of the IIB-MyHC gene.
Deletion of this element had little effect on transcriptional activity in
myotube culture, suggesting that the repressive effect of this element seems to
be restricted to the context of intact adult muscle. Deletion of the CArG
region resulted in a moderate increase of activity in both the soleus and TA
muscles, and a significant decrease of activity in myotube culture. Mutation
of 10 bp upstream of this element caused a similar effect on in vivo
expression. This region may be involved in conferring adult muscle cell
specificity to the IIB-MyHC gene. The proximal 85 bp of the IIB-MyHC promoter
containing an E-box and the TATA box was determined to be insufficient to
confer a significant level of activity to the promoter in either the Ta or the
soleus or in myotube culture. In sum, while the fast-fiber specific element of
the IIB-MyHC promoter was not identified in this project, much was elucidated
on the roles of several evolutionarily conserved elements in transcriptional
regulation of the IIB-MyHC promoter.
A Regulatory Role for MyoD in the Expression of Myosin Heavy Chain
IIB
- Matthew Wheeler
The myogenic transcription factor MyoD
has previously been shown to accumulate in adult fast-twitch muscle. However,
whether MyoD plays an active role in the generation of fiber-type, or is simply
a result of fiber-type remains to be determined. Hindlimb suspension (HS), a
model that induces slow to fast muscle conversion through unweighting, as
utilized to determine the physiological pattern of expression of MyoD and the
fast myosin heavy chain type IIB (IIBMyHC). Soleus muscles, which do not
normally express either MyoD or IIBMyHC, expressed both MyoD and IIBMyHC RNA
after only one week of HS. In vivo injection of promoter-reporter vectors was
used to further characterize the relationship between MyoD and IIBMyHC. The
proximal 300 bp or the IIBMyHC promoter contains at least one element required
for muscle fiber-type specific expression. Within this 300 bp region lies an
E-box, a putative binding site for MyoD. MyoD is shown to form a specific
interaction with this particular E-box. When 4 bp of this E-box is mutated,
binding of MyoD is eliminated. When this mutation is placed within the context
of the IIB promoter-reporter construct, MyoD induction of reporter gene
expression in co-transfected C2C12 cells is reduced 30-fold. This mutation
also decreases activity 67-fold as compared to the wild type promoter within
the fast twitch tibialis anterior muscle following in vivo injection.
Heterologous reporter constructs demonstrate an ability of the E-box to
activate transcription in fast muscle, while elimination of the E-box prevents
this activation from occurring. These data suggest that MyoD can regulate the
expression of the IIBMyHC gene, and indicate a probable causative role for MyoD
in the observed upregulation of IIBMyHC in HS soleus.
Genetic Investigations of cdc14 Suppressors and Directed Two-Hybrid
Analysis of CDC14 and SFP1
- Kyra C. Williams
Cell division cycle (CDC) proteins
are essential for progression of the cell cycle in Saccharomyces cerevisiae
(budding yeast). Each CDC protein acts at a distinct point in the cell cycle
such that cdc mutants arrest growth with a uniform cellular morphology.
CDC-mutants are temperature-sensitive, allowing the cells to continue growing
at the permissive temperature of 25ûC, but inhibiting growth at the
restrictive temperature of 34ûC (Hartwell et al., 1974). This
characteristic allows genetic studies to be performed on the cells that, at
normal temperatures, constrain functional proteins, but still enable the
detection of cell-cycle arrest at the restrictive temperature.
CDC14 is a cdc gene whose activity is not well understood. Although it is
known that CDC14 is required for progression through late anaphase/early
telophase, the mechanism whereby it allows exit from mitosis is not known.
CDC14 encodes a dual-specificity protein phosphatase (Taylor, et al., 1970.)
To further understand the function of CDC14, suppression analysis was used to
identify other proteins involved in the CDC14 pathway. Numerous recessive
cold-sensitive suppressors of cdc14 were identified. One of these suppressors
was found to contain a partially dominant suppressing mutation in SFP1.
Split finger protein 1 (SFP1) has already been found to be capable of
suppressing the CDC14 mutation (Sagasti 1996, Shaw 1996, Paliulis 1997). The
mechanism of interaction between SFP1 and CDC14 is unknown. An sfp1 null
mutation is incapable of suppressing the temperature-dependent lethality of a
cdc14-disruption mutation, indicating that sfp1 does not completely bypass the
activity of CDC14 (Paliulis 1997). It is possible that SFP1 suppresses cdc14
by restoring pseudo-wild type interaction.
Two-hybrid analysis can be used to test whether interaction between SFP1 and
CDC14 occurs. In this system, the gene for one of the proteins thought to be
interacting is fused with the transcription activation domain of either GAL4 or
LexA. The gene for the other protein is fused with the DNA binding domain that
can bind upstream of a reporter gene. When the transcription activation domain
and the DNA binding domain are localized together through the interaction of
the two exogenous proteins, a phenotypic signal is produced from the reporter
gene (Fields and Song, 1988). The SFP1 gene was subcloned into a plasmid
containing an f1 origin of replication in order to use site-directed
mutagenesis to create restriction sites flanking the gene. These sites can
then be used to subclone the gene into a two-hybrid vector to determine if
interaction with CEDC14 occurs.
Larval Foraging Behavior of the White Cabbage Butterfly Pieris rapae
(Lepidoptera: Pieridae)
- Robert Wittenmyer
The larval foraging behavior of the
crucifer-feeding specialist Pieris rapae, the European white cabbage butterfly
(Lepidoptera: Pieridae), and the subsequent pattern of damage inflicted upon
its host plants were investigated. Larvae were observed on the cultivated
hosts broccoli (Brassica oleracea) and radish (Raphanus sativus), and on the
wild hosts Brassica nigra and Hesperis matronalis. Observations of position
and behavior were made throughout the larval life span of P. rapae
caterpillars, and the damaged leaves were digitally stored and analyzed. As
larvae aged, they were found to spend significantly less time feeding and
moving on B. oleracea, B. nigra, and H. matronalis. In general, young larvae
spent considerably more time on the undersides of leaves, and their positional
preference reversed with caterpillar age: older larvae spent significantly
more time in direct sunlight. Damage was shown to be significantly aggregated
on one or a few leaves within 23 of 32 host plant replicates. Although a
majority of the 318 leaves examined had zero or less than 5% of their area
consumed, statistical analysis found that damage was very significantly
concentrated within individual leaves.
Genetic Variation in Arctic Disjunct Subpopulations of Saxifraga
tricuspidata (Saxifragaceae)
- William N. Woodfield
We examined the genetic variation
between different island subpopulations of the arctic disjunct population of
Saxifraga tricuspidata on the northeastern islands of Isle Royale, Michigan.
We mapped an entire S. tricuspidata subpopulation at the southeastern end of
Edwards Island, studied the pollination behavior of S. tricuspidata using
manual pollination experiments, and examined molecular genetic partitioning
between 4 different island subpopulations, using randomly amplified polymorphic
DNA (RAPD) analysis. By analyzing the proportion of ovules that set seed in
experimentally manipulated flowers, we discovered that S. tricuspidata is
self-compatible and that the proportion of seeds set varies according to the
identity of the pollen donor. We used 3 primers on 71 individuals in the
RAPD-PCR analysis and scored 15 polymorphic loci. A calculation of Shannon's
information measure estimated 95.8% of genetic diversity results from
within-population diversity with only 4.2% resulting from among-population
diversity. A calculation of Wright's Fst estimated a value of
0.106, indicating a low degree of structuring between subpopulations. AMOVA
revealed an estimate of 96.65% genetic variation within subpopulations and
3.35% variation between subpopulations, and a [Phi]st, an analog of
Fst, of 0.033. A principal component analysis and the construction
of a phylogram confirmed the lack of subpopulation differentiation. We also
estimated the number of individuals migrating between subpopulations as 7.33
per generation. The results of this thesis indicate a strong mechanism of gene
flow between island subpopulations, a mechanism that is important in
maintaining genetic diversity within the population as a whole.
Mutagenesis of the Interleukin-4 Promoter
- Robert Chang
The expression of Interleukin-4 in mast
cells is under the control of several regulatory elements within the promoter
region. A negative regulatory element named NEG-1 has been isolated using both
in vivo and in vitro methods. Loss of the NEG-1 element in the in vivo
reporter gene constructs resulted in an increase in gene transcription, while
in vitro electrophoretic mobility shift analyses demonstrated that specific
nuclear factors bound to the NEG-1 region. To further understand Interleukin-4
expression in mast cells, mutations of four to six base pairs were introduced
into the NEG-1 region by taking advantage of the M13 bacteriophage life cycle.
The promoter region of IL-4 from -442 to +5 had already been inserted into the
M13 cloning site. The mutations were introduced by incubating the
single-stranded form of the vector with oligonucleotides containing the
mutations. DNA replication was allowed to occur followed by the selective
digestion of the wild-type strand. The strand of DNA containing the mutations
was then used as a template for a final round of DNA replication. The mutated
promoter was excised from the M13 double-stranded form and inserted into a
pCAT-Basic promoter, eventually for use in reporter gene assays to determine
the temporal nature of Interleukin-4 expression.
Elucidation of the Mechanism by which RecA* Mediates the
Autodigestion of LexA in Bacillus subtilis
- Jessica A. Charland
LexA is the 23 kDa autocatalytic
repressor of the Bacillus subtilis SOS regulatory repair system, a network of
20 unlinked damage inducible (din) genes. The RecA protein, activated by
binding ssDNA and dNTP to form activated RecA (RecA*), mediates the
autocleavage of LexA, which then derepresses the SOS system. Based on computer
modeling studies, we propose that RecA binds LexA, forcing Arg166 to fold into
the active site, facilitating general base catalysis of the active Lys165
residue. The work presented here supports our model of how LexA autodigests in
the presence of RecA*. This study involves using site-directed mutagenesis to
evaluate the role of Arg166 in the catalysis reaction. In addition, cysteine
residues were substituted at LexA positions 101 and 148 using site-directed
mutagenesis in preparation for cross-linking experiments with RecA. Residues
101 and 148 are thought to be on the RecA*-LexA binding surface. Assays were
either performed in the presence of RecA to simulate in vivo cellular
conditions. Results suggest that Arg166 is, in fact, important to the cleavage
reaction. The pH profile for wild type LexA suggested a pKa of around 6. This
value was shifted to about 6.7 for mutant RQ166. This shift indicates that
this residue is involved in catalysis.
The Oxidation of Benzyl Ethers via Phase-Transfer
Catalysis
- Bo Yoon Choi
A useful method for oxidizing benzyl
ethers to benzoate esters using potassium permanganate under conditions of
phase-transfer catalysis was investigated. The study encompassed a wide range
of structural systems, ranging from simple aliphatic benzyl ethers to complex
cyclic ethers. Yields were good to excellent. The primary site of oxidation
was benzylic and adjacent to the oxygen atom of the ether. It is believed that
this double activation offers stability to a carbocation intermediate. A
competitive oxidation study between dibenzyl ether and tribenzylamine revealed
that the oxidation of tribenzylamine proceeded faster than that of dibenzyl
ether by about 150 times.
Hetero Diels-Alder Routes to Beta-Carboline
Alkaloids
- Matthew L. Crawley
A concise route to yohimban, a
[beta]-carboline alkaloid, was started in a five-step convergent synthesis.
14-Carboxy-15,20-didehydroyohimban-21-one (27), a direct precursor to
the desired product, was synthesized in three steps. The key step was an
intramolecular annulation of 3,4-dihydro-[beta]-carboline with
tetrahydrohomophthalic anhydride, which had the net effect of a Diels-Alder
addition. The preliminary attempts to decarboxylate (27) to
15,20-didehydroyohimban-21-one (28) were unsuccessful. Other efforts to
synthesis hexadehydroyohimban and berbine through annulation like reactions
with other dienes were unsuccessful.
Synthesis of Organic Electrochromic Materials based on Benzoquinone
Centers and Attempted Synthesis of an Anthraquinone Ligand for a
Ruthenium-Polypyridine Complex
- Matthew D. Kelty
The quenching of the fluorescence
transition A 2[Sigma]+, v = 0 -> X2[Pi], v'
= 3 of nitric oxide (NO) in the presence of halogenated methanes and ethanes
was observed. Measurements were taken on chlorinated methanes (CCl4,
CCl3H, CCl2H2, and CClH3),
fluorocarbons (CF4, CF3H, CF2H2,
CFH3, and C2F5H and
C2F6), and bromofluoromethanes (CBr2F2
and CBrF3) over a range of temperatures from 220 to 295 K. The
rate constant of the fluorescence decay curve is measured at several different
pressures to give a dependence of the decay constant on the partial pressure of
the quencher. From this we can determine the quenching efficiency, reported as
a cross section, of the species being tested. The temperature at which these
measurements are made was also varied, giving a temperature dependence of the
quenching cross sections.
None of the species tested had electronic energy levels close to the energy of
excited state NO. For this reason there was negligible contribution to
quenching due to near-resonant electronic energy transfer. The fluorocarbons
displayed poor quenching efficiency, due to their highly endothermic electron
affinities. The chloromethanes and bromofluoromethanes displayed strong
quenching ability, due to their favorable electron affinities.
The observed quenching behavior was analyzed via both the harpoon and collision
complex models to evaluate the validity of each. The temperature dependent
behavior is best interpreted as the well-depth calculated with the
collision-complex model. Quenching ability, however, is ultimately determined
by the electron affinity of the quencher. This electron affinity affects the
position of the ion-pair potential energy surface, and therefore the position
of the ionic/covalent curve crossing. It was also found that electron
affinities that are calculated from quenching experiments show an incorrect
temperature dependence, which is due to the assumptions inherent in the simpler
energy transfer models.
Further Study of the Cooperativity of Two Negative Regulatory
Elements of the Murine IL-4 Promoter
- Allison C. Lamanna
The production of Interleukin-4
(IL-4) is highly restricted to mast cells and certain T cell subsets; previous
data indicates that the levels of IL-4 produced are under strict
transcriptional control. Studies have demonstrated that there are several DNA
regulatory elements within the 5' flanking region of this gene and that
specific nuclear factors interact with these sequences. In concert, these
various interactions regulate the inducible transcription of IL-4. We have
defined a DNA element designated NEG-1, (-326 to -302 relative to the
transcription initiation start site) that contributes to the down regulation of
this gene in murine mast cells. Our data indicates that this element is the
site of specific nuclear protein(s) binding events in vitro. By mutational
analysis in transient transfection experiments we have defined two subsequences
(A and B) required for the normal functioning of this negative regulatory
element in vivo. Electrophoretic mobility shift analyses were used to explore
the possible interactions of nuclear factors binding to these two sites. The
data to date suggests that, initially, protein factors bind to the A site and
subsequent factors recognize this complex and bind in a cooperative manner.
For complete functional activity of the Interleukin-4 NEG-1 element, both
binding events must occur. Cross-linking experiments indicate that the factor
which binds initially to the A site is approximately 74.6 kD.
Laboratory Studies of SO2 Adsorption on Soot From
-130ûC to -30ûC
- Victoria T. Nicholson
Recently the exhaust from
airplanes has been of much interest. It has been shown that oxidation of
SO2 to H2SO4 occurs much more rapidly in
airplane exhaust than what is predicted by any known mechanism. Using this as
motivation, we are interested in studying the interactions between soot and
SO2 because we believe that soot may be a catalyst for the
SO2 oxidation process. We have performed our experiments under the
conditions that are seen by the airplanes when they are flying near the
tropopause. Our experiments have been performed in the temperature range of
-130ûC to -30ûC. The SO2 pressures allowed to interact
with the soot range from 10-5 torr to 10-3 torr. Our
primary detection tools are a FTIR and a mass spectrometer. They both help to
map the SO2/soot interactions. The results of our experiments have
proven the original hypothesis that SO2 sticks more readily at high
pressures and low temperatures. Furthermore we have been able to quantify our
data using the oscillation pattern of the baseline. From our data we have
found that [theta]sat, one saturated layer of SO2, is
equal to a net coverage of 8ML. Taking into account the roughness of the soot,
the local coverage of SO2 at [theta]sat is ³ 0.07ML
per soot surface, but most likely equal to 0.15ML per soot surface. We have
also observed that at relatively high pressures and temperatures, the "normal"
peaks that we see for SO2 gradually broaden and change to become
triplet peaks. At this point we are not certain what has caused the change in
the spectra, but because the peaks have been blue-shifted we know that
something is strongly interacting with the SO2 which is causing the
oxidation number of the sulfur to increase.
Synthesis and Characterization of Liquid Crystalline Copper(II)
Metal Chain Complexes
- James M. Rowe
This work focuses on the synthesis and
characterization of novel families of metallomesogens based on metal-chain
complexes that show promise as one-dimensional magnetic materials. Liquid
crystalline properties have been introduced into the family of
trans-Cu(pyr)2X2 materials by derivatization of
the pyridyl ligands, and bipyridyl ligands derivatized with both esters (4,4';
5,5'; 3,3',5,5'; 4,4',5,5'; and 4,4',6,6') and dialkylamides (4,4' and 5,5')
have been synthesized in order to make mesogens based on Cu(bipy)X2
systems. When the aliphatic portion of the mesogen in
Cu(pyr)2X2 is introduced via an ester, no mesophases
result. However, when an amide group is used, mesogenic material results. The
structure of the amide-derivatized material is different from solution than
from the melt, due to changes in hydrogen-bonding framework, and only the
latter exhibits mesophases. Further, the inclusion of hydrogen-bonding groups
at positions opposite the metal-coordination sight significantly affects the
environment of the metal, presumably via compression of the bridging Cu-X
bonds. To this point neither ester (5,5' and 4,4',6,6') nor dialkylamide
(5,5') functionalites have been able to induce mesophase behavior on the
Cu(bipy)X2 system, however the synthesis of promising tetraesters
(3,3',5,5' and 4,4',5,5') is near completion.
Turing Patterns in a Templator Mechanism
- Leo L. Tsai
We observe the formation of Turing
patterns in the minimal Templator Model, developed in 1996 by Peacock-L--pez,
Radov, and Flesner. Predictions from stability analysis performed on the model
have led to observations of stable spot, striped, honeycomb, and labyrinth
patterns via computer simulations employing the cellular automata method.
Generalized Forcing in Aperiodic Tilings
- Linden Minnick
Aperiodic patterns occur in many
dimensions. Properties of certain one-dimensional aperiodic sequences, known as
musical sequences, are extremely helpful in understanding similar properties in
aperiodic tilings of higher dimensions. We will use both algebraic and
geometric/graphical methods to prove certain properties about forcing patterns
of musical sequences. These properties may then be applied to our
understanding of forcing patterns in aperiodic tilings of higher dimension, in
particular the two-dimensional Penrose tilings. Properties of tiles forced by
arbitrary initial patches of tiles may also be inferred in conjunction with
other properties of the tilings. In this talk, we discuss many new extensions
to previous results.
INDiGENT: Genetically Refining Expert Neural
Networks
- Brendan D. Burns
Classification systems are algorithms
which have the task of separating a data set into a number of separate
categories. Given a set of rules which classify a problem, INDiGENT utilizes a
genetic search to revise these rules and produce more accurate results.
INDiGENT performs two separate searches. One which modifies the set of input
features available to the learning system and another which modifies the
expert's actual theory. INDiGENT is able to both improve the accuracy of
classification and simplify theory construction when compared to a number of
other systems.
Exploring the Danzer Tiling
- Benjamin C. Chaffin
The Danzer tiling is an aperiodic
tiling of space composed of eight tetrahedra. Though it has no translational
symmetry, it exhibits long-range icosahedral symmetry, a structure impossible
for normal crystals. We will discuss some of the properties Danzer tiling,
including vertex configurations (groups of tiles clustered about and sharing a
central vertex) and the distances between identical regions of a tiling.
Rupiah: An Extension to Java Supporting Match-Bounded Parametric
Polymorphism, This Type, and Exact Typing
- Jonathan L. Burstein
The programming language Java has
gained widespread acceptance throughout the computer industry. Java's type
system, though, is lacking in flexibility. This lack of flexibility limits the
expressiveness of the language, especially for the creation of container
classes. To improve Java's expressiveness, we extend its type system through
the addition of three constructs: match-bounded parametric polymorphism, This
Type, and exact typing. These constructs allow a programmer to write flexible,
extensible, and statically type-safe code. Our current implementation targets
the standard Java Virtual Machine through a source-level translation.
Translation allows Rupiah programs to be run on existing Java installations,
but carries with it a performance cost.
Evolution of a Late Pliocene Lava-Dammed Lake and Pleistocene
Landslides, Espa-ola Basin, New Mexico
- Andrew D. Fagenholz
Deposits of clay and coarser
sediment in the western Espa-ola Basin, north-central New Mexico, record late
Pliocene impoundment and evolution of Culebra Lake. I mapped exposures in
canyon walls and along mesa edges between Los Alamos Canyon and north of Garcia
Canyon in the Puye and White Rock Quadrangles. In order to reconstruct facies
associations and their evolution, I measured stratigraphic sections and
described sediment texture, structure, thickness, and composition. I also
mapped massive slumps of Bandelier Tuff and recorded orientations of individual
blocks. In the laboratory I measured grain size on selected clay samples and
recorded composition of volcanic material.
Paleotopographic reconstruction from elevations and isopach maps indicates that
Culebra Lake inundated a semi-rugged late Pliocene landscape that was probably
a result of semi-arid geomorphic processes. Lacustrine deposits are thickest
in depressions in this landscape, where they overlie alluvial fan deposits of
the Puye formation. Field mapping demonstrates that the presently dissected
toe and midslope of the Puye fan are covered by subaerial and lacustrine
deposits up to 30 m thick over >50 km2 in the study area. Basal
silt and fine sand probably accumulated when Culebra Lake was smaller than its
maximum size of ~1,000 km2. Widespread, massive, illite/smectite-
and kaolinite-rich clay indicates that low energy sedimentation of Colorado
Plateau-derived detritus dominated distal Culebra Lake zones at depths >15
m; elevations of clay suggest that Culebra Lake-level stood at ~6400' for
>5,000 years. Irregular sediment yields of piedmont drainages in a semi-arid
climate and minor lake-level changes generated local coarsening up sequences in
nearshore and shoreline zones that indicate east and south lakeshore migration.
Sand and mudflow thickness indicate that sediment was delivered from the
western piedmont in channels that concentrated sediment in fan-deltas and
deltas along the lakeshore.
Elevations of materials that truncate lacustrine sequences suggest that
significant volumes of Culebra Lake deposits locally were removed during the
~0.5 Ma between lake drainage and eruption of the 1.6 Ma Bandelier Tuff. Slump
complexes that developed in the Bandelier above Culebra Lake clay probably
began to fail when tributaries cut into and through lake deposits in
Pleistocene time. Slump complex morphologies suggest that block formation
probably propagated away from drainages as lateral support was removed
sequentially. Slumping has completely removed Bandelier material from several
mesa surfaces. Lacustrine deposits probably have controlled finger-mesa
morphologies into the present.
The Upper Bandelier Tuff: Pyroclastic Flow Dynamics and Landscape
Evolution, Puye Quadrangle, New Mexico
- Stephanie K. Kampf
This study is an integrated
examination of volcanic and erosion processes associated with the Lower
Pleistocene Upper Bandelier Tuff in the Puye quadrangle, New Mexico. The area
contains some of the most distal remaining deposits of Upper Bandelier Tuff.
Published tuff classification systems for proximal areas apply imperfectly
here. My study thus provides significant insights into pyroclastic flow
mechanisms in distal areas, the landscape over which flows traveled, cooling
unit characteristics and stratigraphic boundaries, and continuing evolution of
the landscape. These analyses are based upon field observations and thickness
measurements of Upper Bandelier cooling units in the Puye quadrangle and on
adjacent areas of Los Alamos National Laboratory (LANL) as mapped by M.A.
Rogers (1995).
Structure contour and isopach maps for Upper Bandelier cooling units suggest
that the pre-Tshirege land surface exposed drainages trending W-E in the
northern Puye quadrangle area and progressively cutting further toward the
southeast in the southern Puye and LANL areas. Two broad canyons cut through
the study area north of present Guaje Canyon, the largest of which might be
considered a "paleo-Guaje Canyon." South of present Guaje Canyon, another
major canyon, "Otowi Canyon" trended to the southeast. In the LANL area, one
or more southeast-trending canyons may have existed in the central zone. The
largest apparent drainage trended east in western LANL and bent almost directly
south to connect with the Early Pleistocene Rio Grande. Little evidence of
smaller tributaries remains, but one likely connected with paleo-Guaje canyon
in central Puye quadrangle. Isolated remnants of Upper Bandelier furthest east
in the Puye quadrangle represent fills of two small tributaries, one trending
west to east and the other north to south.
Upper Bandelier pyroclastic flows were greatly influenced by this topographic
base in the eastern Pajarito Plateau area. The first flow unit shows dramatic
thickness fluctuations that reflect the paleo-topography. Unit 1 probably
traveled through the Puye quadrangle in two major flow lobes constrained by
paleo-Guaje and Otowi Canyons. Where these lobes intersect in a zone of
relatively thin tuff cover, remaining unit 1 deposits contain abundant pumice
concentrations and surge deposits. Subsequent flow units traveled over a
relatively flat surface but still remained slightly constrained by topography.
Unit 2 may have flowed through the northern Puye quadrangle in separate lobes
traveling down remaining topographic depressions.
Following emplacement of the Upper Bandelier, subsequent drainage incision
shifted in orientation and direction from its pre-Tshirege position. The deep
incision of Guaje Canyon has formed through a zone where the cover of tuff is
quite thin, whereas the most distal outcrops of Tshirege remain where thick
flows of Upper Bandelier filled major drainages.
The Development of Cleavage and Graphite in Pelitic Schist near
Taconian Thrust Faults, Mount Greylock, Massachusetts
- Eliza S. Nemser
During the Ordovician Taconian
orogeny, thrust faults carried the Late Proterozoic to Cambrian Greylock Schist
westward over Cambrian and Ordovician rocks of the Stockbridge and Walloomsac
Formations. Ratcliffe et al. (1993) interpreted the structure in the Greylock
Massif as a recumbently folded thrust; this model was used to account for
complex repetitions of the Greylock Schist and the Stockbridge and Walloomsac
Formations. Deformational fabrics indicate that the structure may instead be
dominated by cleavage in the Greylock Schist, which overprints an earlier
schistosity, is most strongly developed near fault contacts and is only weakly
developed in the cores of proposed recumbent folds, suggesting that these rocks
were not folded post-emplacement. Textural evidence indicates that many of the
rocks reached garnet grade prior to or during the development of the
crenulation cleavage and were subsequently retrograded.
The repetitions of units may be explained by a model in which slivers of the
Stockbridge Formation were dragged up along imbricate thrusts as the Greylock
Schist overrode the Stockbridge Formation. Faults are typically mapped at the
upper contact of the Walloomsac Formation, which is mapped based on the
presence of graphite. However, graphite occurs in areas mapped as Greylock
Schist and Stockbridge Formation as well as Walloomsac Formation; in each of
these units, graphite-rich material is interspersed with graphite-poor
material. The complex distribution of graphite in the rocks of the Greylock
Massif suggests that graphite may not be a reliable stratigraphic marker. On
the basis of geochemical models, I propose that graphite precipitated from
carbon-bearing metamorphic fluids which migrated through fracture systems
localized near faults during thrusting. Most of the graphite that was already
present in these rocks prior to Taconian deformation and metamorphism must have
been mobilized and redistributed during thrusting, as graphite is often
concentrated in the planes of the crenulation cleavage. Much of the mapped
Walloomsac Formation on the Greylock Massif may be reinterpreted as
graphite-rich zones within the Greylock Schist and Stockbridge Formation;
faults my be mapped in zones of particularly high graphite content.
Rates of Holocene Aggradation and Pedogenesis, Southeastern Puye
Quadrangle, New Mexico
- Catherine A. Riihimaki
Middle to late Holocene
terraces and alluvial fans expose sequences of buried soils developed in sandy
alluvium and fine eolian sediment along tributaries to the Rio Grande in the
Puye 7.5' Quadrangle, northern New Mexico. Sedimentary sequences along arroyos
and on the broad alluvial fan record mainly aggradation and equilibrium during
the Middle to Late Holocene. The 14C ages of disseminated charcoal
suggest that channels and alluvial fans aggraded from 2 to 7 m above modern
arroyo levels during middle Holocene time. Sparse cultural and vegetation
evidence indicates that channel downcutting began in historic time.
Soils formed on terraces during periods of relative surface stability and were
buried by subsequent aggradation. Aggradational sequences contain numerous
buried soil profiles, including one 3-meter sequence of 9 buried soils. Field
evidence shows that buried soils are a few centimeters to decimeters thick and
consist mainly of A/C profiles, Bw horizons, and weakly developed Bt horizons
that contain carbonate coatings along fractures and pores. Laboratory analyses
of texture and extractable constituents indicate that soils from the semiarid
study area contain abundant fine material, CaCO3 and relatively
little extractable iron compared with Holocene soils that developed on the
adjacent Pajarito Plateau under more temperate climates. Silt plus clay
content ranges from 5 to 85%, CaCO3 content ranges from 0.14 to
8.79%, and Fe2O3d content ranges from 0.12 to 0.38%. The
abundance of fine material indicates that the carbonate and extractable iron
contents in buried soils are primarily controlled by eolian input and that
pedogenic processes are minor in the young soils of the semiarid environment.
The 14C ages and laboratory analyses from buried soil profiles
enable estimates of the rate of development of pedogenic characteristics such
as loss on ignition (LOI), extractable iron, and CaCO3 and the rate
of aggradation during middle Holocene time at one location. Calculations
indicate rates of 5.8 g/cm2/ky for LOI, 0.072 g/cm2/ky
for Fe2O3o, 0.38 g/cm2/ky for
Fe2O3d, 4.9 g/cm2/ky for CaCO3, and
1.2 m/ky for aggradation during a 1.44-ky period. The age of nearby undated
deposits and surfaces can be estimated using the degree of soil development at
dated sites and continuity of aggradational sequences. These ages suggest that
exposed deposits extend from the Middle Holocene to historic time, and may
locally span the Holocene.
The 14C ages and estimated ages from degree of soil development
suggest the following Holocene history of aggradation and incision in the
southeastern Puye Quadrangle: delivery of coarse alluvium from upstream sites
from ~8 to 5 ka, accumulation of silt-rich alluvium and eolian sediment from ~5
to 3 ka, abundant eolian activity from ~3 to 2 ka, and incision beginning at
~0.1 ka. Aggradation is out of phase with upstream terrace formation on the
Pajarito Plateau, but in phase with aggradation and incision in nearby Tesuque
Valley, New Mexico. Rates of accumulation of CaCO3 suggest the
sequence of response to climate change of fluvial systems of the Puye
Quadrangle is high eolian activity, erosion upstream, and deposition downstream.
Geochemistry and Tectonic Setting of the Early Proterozoic
Metavolcanic Rocks of the Arkansas River Canyon, Howard to Royal Gorge, Central
Colorado
- Katherine M. Wearn
The Arkansas River Canyon area of
central Colorado contains a significant and previously overlooked suite of
Early Proterozoic bimodal metavolcanic rocks in the section extending 50 km
upstream (west) from the Royal Gorge to the Pleasant Valley fault near the town
of Howard. The felsic and mafic units are interlayered with a well-exposed
series of biotite-quartz-feldspar gneisses, quartzites, and metapelites. The
layered rocks were deformed and underwent regional sillimanite-grade
metamorphism prior to the intrusion of the Garrell Peak pluton, which
cross-cuts the metavolcanic units and gives them a minimum age of 1.65 Ga. The
predominantly aphyric felsic units are characterized by primary fragmental
textures and locally by relict flattened pumice lapilli. Amphibolites
represent mafic flows and gabbroic sills; no pillow structures were observed.
Trace element data for 17 felsic samples by XRF and 12 by INAA show enrichment
in both LILEs and HFSEs, and depletion in Sr, P, Ti, and Sc in MORB-normalized
spider plots. REE diagrams show LREEs at about 100x chondrite and only
slightly enriched over HREEs (LaN/YbN²5, along with
small to moderate negative Eu anomalies. Geochemically these rocks closely
resemble the less deformed Early Proterozoic aphyric metarhyolites near Salida,
15 km west of the western edge of the studied section (Boardman and Condie,
1986) and near Gunnison, 120 km to the west (Condie, 1986). The ranges and
averages of most trace elements in the Arkansas River rocks are consistent with
those of mature island arcs and active continental margins, both of which are
components of regional tectonic models for Colorado showing rapid accretion of
arc systems onto an enlarging continental during the Early to Middle Proterozoic.
Decompositions Via Linear Recurrences and Their Associated
Asymptotics
- Kariane Calta
A result from the early 1950's states
that every natural number can be expressed as a sum of Fibonacci numbers.
Later work determined the average number of terms needed in such a
representation. In this thesis we extended and generalized these results by
replacing the Fibonacci sequence by N-term linear recurrences having
coefficients equal to one. Generalized two term recurrences with arbitrary
coefficients are also investigated.
The Fibonacci Sequence Modulo p
- Heath R. Dill
In this thesis we study the period
length of the Fibonacci sequence modulo p, where p is a prime. In 1960, Wall
produced divisibility results for such lengths in terms of p that naturally
give rise to upper bounds for the period lengths. Here, using different
methods, we produce new divisibility results which in many cases produce
improved upper bounds for the period length. Fundamental to our method is a
new algebraic structure on consecutive pairs of Fibonacci numbers.
On Parallelograms and Lattice Points in the
Plane
- Mimi Huang
This thesis investigates the areas of
parallelograms in the two-dimensional plane. We consider parallelograms with
center at the origin and directions of sides given with no interior integer
lattice points except the origin. Szekeres found the supremum of the areas of
such parallelograms and proved that the supremum can be at a particular
direction of sides. Disregarding this particular direction of sides, we can
attain a higher supremum for the areas of such parallelograms. Possible
supremums of such parallelograms and the direction of sides at which the
supremums are attained is shown in the paper. Cost minimizing networks model
certain behavior of immiscible fluids in the plane. This paper proves the
bound on the number of regions meeting around a point.
Z2 Actions, Flows, and
Ergodicity
- Andrew Raich
This thesis explores examples from
ergodic theory. We investigate infinite measure preserving and nonsingular
actions, with the primary focus on actions of the group Z^2. Chapter 2 studies
finite measure preserving actions on the unit interval. Chapter 3 studies
infinite measure preserving Z^2 actions to generate actions for which every
direction has infinite ergodic index. We also construct a power weakly mixing
Z^2 action, called the multistep action. Chapter 4 applies techniques of
Chapter 3 to nonsingular type III_lambda Z^2 actions to generate a Z^2 Chacon
action for which the basis transformations have infinite ergodic index.
The Planarity of Subgraphs in Outer-facial
Drawings
- Tristan Boardman Smith
This work is concerned with the
problem of determining whether a given graph admits certain types of
outer-facial drawings. There is a well-known characterization of those graphs
which admit an outer-facial drawing having no edge crossings. Here we
characterize those graphs that admit outer-facial drawings such that a given
subgraph will have no edge crossings. We also consider the problem of whether
a graph admits an outer-facial drawing that simultaneously minimizes the number
of edge crossings and places a Hamiltonian cycle on the outer face. We provide
a method that solves this problem for an infinite family of graphs.
The Period 1 to Period 3 Transition Through Chaos in a Mode-Locked
Ti:Sapphire Laser
- Christopher N. Elkinton
Chaotic behavior was observed
using an ultrafast mode-locked Ti:sapphire laser. The laser was Kerr lens
mode-locked and produced pulses of duration on the order to 50 femtoseconds.
Following a known route to chaos--that of the transition from period 1 to
period 3 regimes--we studied temporal, spatial, and spectral data. We used
return maps, phase portraits, and power spectra as tools to allow us to observe
behavior within the laser system characteristic of chaos. Analysis of this
data leads us to conclude that we have observed a realm of chaos between
regions of period 1 and period 3. Included in our data are pulse trains,
optical spectra, time-averaged and pulse-resolved spatial profiles, and
interferometric autocorrelations that help to characterize the period 1 and
period 3 behaviors.
Behavior suggesting coupled transverse modes was also observed. By comparing
pulse trains on opposite sides of the beam, spatial energy exchange was seen.
We hypothesize that this transverse mode coupling affects the periodicity of
the system.
Spatial and Temporal Nonlinear Dynamics in Kerr-lens Mode-locked
Ti:Sapphire Laser
- Robert A. Jenks
Passive mode-locking techniques, which
to date have produced the shortest laser pulses, depend fundamentally on
optical nonlinearities for their operation. Passively mode-locked lasers have
also been observed to exhibit nonlinear dynamical and chaotic behavior. In
this thesis, a numerical model that simulates nonlinear dynamical behavior is
developed. The model relates the spatial and temporal nonlinearities operating
in a mode-locked Ti:sapphire laser directly to its nonlinear behavior. The
model also attempts to incorporate novel observations of energy exchange
between simultaneously oscillating transverse spatial modes by using a coupled
cavity analogy. Experimental measurements that can test the predictions of the
model are discussed, and a data acquisition system that resolves the individual
pulse characteristics necessary to make these measurements is presented. The
predictions of the model are qualitatively tested using the data acquisition
system, and shown to be in general agreement with the data.
A Mode-Locked Erbium-Ytterbium Optical Fiber
Laser"
- Aaron J. Kammerer
This thesis reports the improvements
made to a mode-locked Er-Yb fiber laser. It is believed that mode-locking has
indeed been achieved since the laser produces stable pulses of the minimum
detection duration of the photodetector and oscilloscope in the laboratory of
approximately 3.5 ns. The pulses have a fundamental repetition rate of 3 MHz
that corresponds to the rate of one pulse at a time traveling around the laser
cavity of 70 m. The pulses are extremely sensitive to polarization and fine
adjustment of two polarization controllers is imperative to realize mode-locked
operation. Verification of actual pulse duration through autocorrelation is a
goal for future research.
Photoassociation Spectroscopy of Ultracold Na and the Development of
Equipment to Laser-Cool Rb
- Christian A. Murphy
Two separate but related projects
are described in this thesis. First, we investigated the high rotational and
vibrational energy levels of the 1g(3S + 3P) state of Na2
which exhibit large internuclear distances. These states are only accessible
using photoassociation spectroscopy of ultracold (Å 0.5 mK) atoms. We
used an apparatus at the National Institute for Standards and Technology in
Gaithersburg, MD to do the spectroscopy. Our main goal was to find the
frequencies of these states to a greater precision than had been achieved
previously. The data we collected is presented here.
Second, at Williams we are building an apparatus to do photoassociation
spectroscopy of Rubidium. The design and construction of a grating tuned diode
laser that has a stable enough frequency to sustain a trap is described. We
have successfully constructed a laser that has a frequency stability of 5.0 MHz
which was, in fact, our stability goal and is sufficient for our purposes.
Design and Construction of an Atomic Beam Apparatus for Precise
Spectroscopy of Thallium
- Peter C. Nicholas
This thesis details the design and
construction of an atomic beam system that will be used to study thallium
atomic structure in order to guide the refinement of thallium wavefunctions.
Precise tests of the standard model's predictions of electroweak interactions
in atomic systems require both precise measurements of effects due to the weak
interaction and precise atomic wavefunctions. In atoms other than hydrogen,
especially non-alkali atoms, approximate theoretical wavefunction calculations
depend upon precise measurements of atomic parameters. Several atomic
structure measurements using the soon to be completed atomic beam apparatus are
discussed. An experiment to search for T-odd, P-even long range
electron-nucleus interactions is also presented. Details of a laser frequency
calibration technique, involving least squares parameter estimates based on
transmission data from a Fabry-Perot interferometer, are given.
Precise Measurement of the Electric Quadrupole Amplitude Within the
6P1/2 to 6P3/2 Transition in Atomic
Thallium
- Leo L. Tsai
An experimental measurement of the
electric quadrupole (E2) component of the 6P1/2 to 6P3/2
transition in atomic thallium is presented. Motivation for this and future
measurements of thallium atomic structure stems from a recent 1% measurement of
atomic parity nonconservation (PNC) within this same transition. In this
experiment, an evacuated quartz cell containing thallium was heated to about
900¡ C. Light from an external cavity diode laser passed through a
polarimeter containing the vapor cell and a longitudinal magnetic field. The
relative size of E2 compared to the known M1 (magnetic dipole) amplitude was
determined through careful line shape analysis of very high resolution
absorption and Faraday rotation spectra. The preliminary value for [chi],
defined as the ratio of E2 to M1, is: [chi] = 0.2358 ± 0.0006 ±
0.0028. This result is used to resolve a discrepancy between PNC measurements
performed at the University of Washington and at Oxford. Based on our value
for chi, a correction factor is suggested for the Oxford PNC measurement that
brings the two results into statistical agreement.
Body-Focus in Women
- A. Katherine Bair
Two studies were conducted. The
first examined the body-, diet-, weight-, and exercise-focused messages in
today's most influential print media sources. The second examined (1) the
relationship of those influences to the self-schemata of college-age women and
(2) the reactions of participants to women of different body types and eating
habits in relation to the participants' body-focus. Analysis of
Glamour, Cosmopolitan, and Good Housekeeping showed
minimal increases in some exercise-focused messages and in some non-diet,
non-exercise weight loss messages (diet pills) but found no change in the
number of diet messages. The second study showed no relationship between
fashion magazine readership and body-focus but did show significant
relationships between body and meal size of a pictured woman and the number of
body- and food- related remarks of a female observer. However, these
significant results did not support the hypotheses. Limitations of the study
and suggestions for future research are included.
Self-Presentation of Academic Achievement at Girls' Boarding
Schools: An Exception to Female Modesty?
- Andrea Burns
This study examined whether the
established trend of "female modesty" in public situations would be found in
high school girls attending single-sex boarding schools. Ninth grade students
at four girls' boarding schools met with the experimenter in groups of 2 to 4
students at a time. During the course of an interview, they were asked to
predict the grades they would receive at the end of the first semester. This
was done under one of three conditions: a private condition, in which the
predictions were written anonymously on note-cards, an anticipated public
condition, in which the predictions were written, but with the anticipation of
discussion with the group, and a public condition, in which predictions were
made out loud. Following the interview, participants completed a three-part
questionnaire, which measured their self-reported concerns and motivations
during the interview, their gender-role orientation, and the degree to which
they defined themselves through their relationships. It was hypothesized that
participants in the public condition, those participants who were highly
feminine, and those who were highly relational would predict significantly
lower grades. Further, it was hypothesized that those participants in the
public condition would demonstrate more affiliative behaviors, and make more
modest remarks during the interview. It was found that, contrary to the
hypothesis, participants in the anticipated public and public conditions
significantly over-predicted their grades, while participants in the private
condition were accurate. The hypotheses regarding a relational orientation, and
participants' affiliative behavior and modest remarks during the interview were
supported. The results suggest that the single-sex environment may elicit a
different pattern of self-presentational behavior than coeducational situations.
The Effects of Nonverbal Cues and Ethnicity in Triggering In-Group
Leader Preference
- Grant W. Farmer
This research examined the effects of
nonverbal gestures. It tested the hypothesis that when a subject must rely
only on nonverbal cues as his/her information about others, this will
instinctively trigger genetically wired information related to the nonverbal
cues which will allow the subject to infer the level of similarity between
himself and others. More specifically, the study looked at whether these n
nonverbal clues would trigger wired information relating to a leader schema
based on an innate desire to identify with others similar to us, and, if this
is in fact true, would these automatic processes have an impact on voter
preference? The study exposed 132 Williams College undergraduates to a
political debate. The debate was debate was between two men, Paul Schell, who
is Caucasian, and Charlie Chong, who is Asian. The videotape was edited into
six different media variations in order to isolate specific channels of
information presented to the subjects. The subjects were asked to rate each
candidate overall on fifteen overall characteristics, and depending on which
variation the subjects were exposed to, they also rated the two men either on
appearance, voice, or both. It was predicted that of all the measures the
visual variation would reveal the highest ingroup preference as measured by
higher ratings for the same race candidate. The results indicate that ingroup
preference is strongest in the visual variation in overall performance and
overall leadership measures. The data also suggest that ethnicity plays a role
in affecting subjects' perceptions of leadership, which in turn, affects voter
preference. Discussions of secondary findings and alternative explanations are
also included.
"I Didn't Do It!": Effects of Training on Judgments of Truth and
Deception in the Interrogation Room
- Christina T. Fong
The present experiments investigated
whether trained and naïve observers can distinguish between true and false
denials in a police interrogation. Study 1 tested the claims that observers
trained in the verbal and nonverbal analysis of statements made in
interrogation can distinguish between truthful and deceptive crime suspects.
In Phase One, 16 participants committed either a mock crime or a related but
innocent act. These suspects were then arrested and interrogated. In Phase
Two, their videotaped interrogations were shown to 40 trained or naïve
observers. The results indicated that trained observers were less accurate
than naïve observers--but they were more confident and cited more reasons
for their judgments. Study 2 replicated this study for individuals interacting
in naïve or trained groups. Again, training had a negative effect on
judgment accuracy, but it did not significantly affect confidence levels.
These results shed doubt on the belief that police interrogators or juries can
accurately distinguish between guilty and innocent suspects during an initial
interview. Gender Issues and Identity Development.
The Effect of Patterns of Behavior on Self
Control
- Kristin M. Frentzel
Working with the delay discounting
model of impulsiveness, in which impulsiveness is described as the choice of a
smaller, earlier reward (SER) over a larger, later reward (LLR), we wanted to
determine whether establishing a pattern of behavioral choices favoring larger
rewards can increase a person's self-control. Three studies tested this
patterning effect. In Experiment 1 (n=75), participants received a single
randomly selected monetary reward at the end of the experiment. To examine the
patterning effect, delays to both rewards were initially long, and were then
gradually decreased so that a pattern favoring choices of the LLR was
established. Again in Experiment 2 (n=40), each participant received a single
randomly selected monetary reward. Here, we used a "staircase procedure" to
change the value of the smaller reward in incremental steps while keeping the
delay to both rewards fixed, thereby establishing patterns favoring LLR choices
when SER values were small. Experiment 3 (n=5) differed from the other two
experiments in that participants received food rewards, and they were
reinforced after each patterning trial. The patterning trials were similar in
structure to those of Experiment , but they were offered in "real time" with
participants being telephoned on an approximately weekly basis and offered a
choice trial.
Experiments 1 and 2 found no evidence of a patterning effect, but Experiment 3
provided suggestive evidence that patterning can, in fact, enhance
self-control. The data suggest that simple response repetition patterns are
not sufficient to increase self-control; rather, each element of a pattern of
choices must be reinforced.
To Stroop Or Not To Stroop: A Novel Experimental Paradigm For
Studying Impulsivity
- Justin Houk
Relatively few studies with humans have
examined impulsivity and self-control in controlled, laboratory settings. This
may be due to the fact that we lack a good paradigm for eliciting
impulsiveness. A new paradigm, the Escape-from-Stroop task, was designed and
tested to see if it both supported as well as provided a way to advance current
theory on impulsiveness. In this paradigm, participants were given an
extremely difficult and aversive task to perform, based on the Stroop task.
Impulsiveness was determined by how subjects chose to escape from the task. In
Experiment 1 (n = 48), participants were found to (1) make choices consistent
with the current theory of impulsiveness-that being that they preferred a
larger, later reward to a relatively small smaller, sooner reward, but
preferred a smaller, sooner reward when it was almost as large as the larger,
later reward-and (2) be affected by a pattern of impulsive or self-controlled
choices. In Experiment 2 (n = 38), it was shown that the Escape from Stroop
task could be effectively used in situations with a discrete short term reward,
but a long term conflicting reward that was spread out over time. Future
applications of the new paradigm were discussed.
Modulation of the Short and Long-term Consequences of Maternal
Separation by the Neurosteroid Allopregnanolone
- Elizabeth Ward Kajunski
Early stress, in particular
that of maternal separation, has been found to exert persistent and detrimental
effects upon the brain. This thesis investigated the potential therapeutic
actions of concomitant administration of the neurosteroid allopregnanolone, a
potent positive modulator of the GABAA receptor, with the stress of
maternal separation. Subjects were both 7 day-old and adult rats, divided into
separated and non-separated conditions from days 2-6. Within each group of
separated and non-separated rats there were rats receiving no injection,
subcutaneous vehicle injection, and subcutaneous injection of allopregnanolone,
5mg/kg. On day 7, rats tested as neonates were given either no injection,
vehicle, or one of 2 doses of allopregnanolone, intracerebroventricularly.
Their vocalizations and behavior were then monitored. Adults were tested on
the elevated plus-maze and monitored for activity. There were no significant
differences in behavior observed between separated and non-separated controls.
Interestingly, however, non-separated pups given allopregnanolone daily showed
decreased anxiety in the PN7 test and a tolerance to the drug. Adult males in
the same neonatal condition also showed a persistent anxiolytic effect of the
drug. These results, while not supporting our hypothesis, suggest a functional
change in GABAA receptors due to handling and postnatal exposure to
allopregnanolone. In addition, they point towards further research into the
neurological mechanisms underlying the potential stress-protective effects of
handling.
Towards the Development of an Informant Questionnaire Sensitive to
Alzheimer's Disease
- Sarah C. Lurding
The goal of the present study was to
develop a brief questionnaire that would be a sensitive screening instrument
for Alzheimer's disease. With the rise in prevalence of AD, there is a need
for a simple and short screening battery that could be implemented in a
primary care setting. This study evaluated the Alzheimer's Disease Caregiver
questionnaire (ADCQ) which is a self-administered, informant completed 56
question checklist that takes no more than 15 minutes to complete. It includes
questions on memory, confusion and disorientation, geographic confusion,
aphasia, apraxis, and personality changes, all of which are areas known to be
disturbed in AD patients. The subjects who completed the ADCQ were either
caregivers of AD patients (n=42) who were referrals to the Memory Clinic at
Southwestern Vermont Medical Center in Bennington, VT or informants of healthy
elderly controls who were community residing elderly (n=40). CART analysis was
used to distinguish which questions were the best predictors of the diagnosis.
The three discriminatory questions found by CART classified the sample with a
sensitivity of 93% and a specificity of 100%. Taking the question from each
axis that was most frequently answered "yes" to by AD caregivers, the sample
was classified with a sensitivity of 98% and a specificity of 95%. Using all
of the questions of the ADCQ, the sample was classified with a sensitivity of
91% and a specificity of 95%. This evaluation also found a high degree of
test-retest reliability. There was a 95% consistency between informants'
answers on the first and second questionnaire and there was a high degree of
consistency for each question with a 95% consistency for all questions
combined. The ADCQ shows promise as an accurate screening instrument sensitive
to AD. Further data collection will identify 10-20 predictive questions that
will ultimately become the ADCQ and which will be further validated. In
further research, the ADCQ's value will be assessed in primary care setting.
Spirit of the Game: The Psychology of Gender and
Competition
- Sarah E. Nelson
Ultimate Frisbee was used as a medium
to study the behavior and reasoning of men and women when confronted with
potential conflict situations in athletic competition. High and low-level
single-sex games were observed and videotaped, and a questionnaire was
distributed to players from across the nation. For each game observed,
frequencies of foul calls and contests were recorded, and for each taped game,
discussions and conflicts were coded, as well as number of fouls actually
committed (whether called or not). The questionnaire included questions about
willingness to make and contest calls and certainty needed to make such calls,
as well as more general questions about reasons for playing and definitions of
"spirit of the game," the underlying philosophy of Ultimate. In the observed
games, men called significantly more fouls than women, across levels, but there
was not significant difference between the sexes or levels in frequencies of
contests. When corrected for number of fouls actually occurring, as coded on
the videotapes, the difference in foul calls also seemed to disappear.
However, men and women answering the questionnaire differed significantly in
their reports of willingness both to call and contest fouls -- men were more
willing to do both. Men and women also differed slightly in their reasons for
playing Ultimate when level of play was considered. Club women gave more
competitive reasons that college women, while club and college men did not
differ. Club men gave more social reasons than college men, while club and
college women did not differ. Men also gave more game-oriented definitions of
"spirit of the game" than women, who gave more person-oriented definitions of
"spirit of the game" than women, who gave more person-oriented definitions.
Both the relation of these findings to gender differences in aggression,
assertion, and styles of interaction, and also the malleability of these gender
differences are discussed in the thesis.
Consequences of maternal Separation for Immunological Responses to
Later Stress in the Rat
- Cynthia Jean Osterling
Maternal separation produces
behavior agitation, increases in circulating levels of stress hormones, and
impairments of immune function. Early separation has also been shown to result
in behavioral and physiological vulnerability to subsequent stressors in later
life. In this study, two measures of immune function, numbers of natural
killer (NK) cells in the spleen and mitogen-stimulated production of the
cytokine interleukin-2 (IL-2) were determined in adult rats that a) underwent
maternal separation as neonates; b) underwent maternal separation as neonates
and a brief swim stress as adults; c) underwent a brief swim stress as adults;
and d) did not undergo either stressor. IL-2 production was significantly
lower in rats that underwent acute swim stress (<.05). In contrast, NK cell
numbers were similar in all treatment groups. Immunological sensitivity to
swim stress in the rats that experienced maternal separation was not increased.
However, when substantial systematic variability in both NK cell numbness and
IL-2 production among different litters of rats were taken into account
statistically, analyses revealed significantly lower levels of IL-2 in rats
that underwent maternal separation compared to unseparated rats. Finally,
administration of the anxiolytic neuroactive steroid allopregnanolone (5 and 10
mg/kg) did not alter the immunological effects of acute swim stress. The
results of these experiments are consistent with previous reports of reduced
functional immune responses following acute stress, but they provide only weak
support for the hypothesis that early traumatic experience produces lasting
immunological vulnerability to stress.
Can Early Stress Alter the Neurosteroid-GABA System in Neonatal and
Adult Rats
- Sharon H. Rackow
The neuroactive steroid
allopregnanolone (3a-hydroxy-5a-pregnant-20-one) has been shown to be involved
in the neurochemical stress response via its positive modulation of the
GABAA receptor complex. This experiment investigated whether
response to the neuroactive steroid allopregnanolone, a positive modulator of
the GABAA receptor, would be altered in rats previously exposed to a
chronic stressor - daily seven hours of maternal separation. Rats were tested
as neonates (one week) and as adults using measures of both emotional behavior
and activity.
In
neonates, allopregnanolone, as previously reported by this laboratory,
decreased the number of ultrasonic vocalizations after a brief maternal
separation. Non-separated pups vocalized more and were more active then
separated pups, but were not more sensitive to allopregnanolone on either
measure. As adults, the previously separated rats had a greater grooming
response to a ten minute cold water swim test than non-separated subjects;
again, there was no difference in the anxiolytic effect of allopregnanolone.
These results suggest that while early maternal separation stress does produce
a habituation response in neonates and a possible long-term sensitization
response to later novel stress in adults, behavioral differences may not be due
to developmental alternations in the neurosteriod system.
A Description and Preliminary Investigation of the Use of
Solution-Focused Therapy in a Partial Hospitalization
Program
- Kristie A. Rogers
This study was conducted at the
Partial Hospitalization Program (PHP) at the Berkshire Medical Center. The PHP
generally treats patients who otherwise might be (and usually in the past have
been) hospitalized for Bipolar disorder, Unipolar depression, personality
disorders and related self-destructive behaviors, and other varied serious
disorders. The therapists use Solution-Focused group therapy to help patients
to think differently about themselves, their problems, and the solution to
those problems. The focus of this research was primarily cross-sectional and
examined two main questions: 1) Are certain types of clients' attributions
correlated with hopelessness, and with their level of functioning? and 2) Are
there differences in the types of attributions made based on diagnosis? Thirty
clients enrolled in the program completed a set of measures including the
Constructions of Problems Scale, the Basis-32, and the Beck Hopelessness Scale.
The preliminary results suggest that there is a negative correlation between
solution-focused thinking and hopelessness. In addition, the clients' level of
functioning is inversely related to their degree of hopelessness. Other
predictions regarding problem constructions and hopelessness were not
supported. On a more exploratory note, four small case studies were included
which examined cognitive changes that appear to have accompanied the
Solution-Focused Therapy.
Stress and Antibody Responses in a Genetic Animal Model of
Depression
- Joanna R. Stevason
Major depression is associated with
increased susceptibility to infectious illness and impairments of immune
function. The aim of the current study was to examine whole-body antibody
responses to immunization in Flinders Sensitive Line (FSL) rats, a promising
animal model of depression, and in control Flinders Resistant line (FRL) rats.
All animals were immunized with the novel protein antigen keyhole limpet
hemacyanin (KLH), and blood samples ere drawn before immunization and 3,5,7, 11
and 14 days after immunization. Anti-KLH specific IgM and IgG serum antibody
titers were then determined by enzyme-linked immunosorbent assay (ELISA). In
addition, to determine strain differences in secondary antibody responses, the
same animals were reimmunized 2 months later, and blood samples were drawn at
the same intervals for determination of antigen-specific IgG titers. The FSL
rats showed significantly lower levels of antigen-specific IgM and IgG after
primary immunization and lower IgG levels after secondary immunization
(<.05). Finally, no differences in specific antibody production in were
observed in animals subjected to a pharmacological stress
(intracerebroventribular administration of corticotropin-releasing hormone)
compared to control animals. These experiments are the first to demonstrate
substantially lower in vivo antibody responses in the FSL rats, and they
provide support for the utility of this animal model in understanding
physiological processes that may contribute to impaired immune function in
clinical depression.
Pessimistic Explanatory Style and Athletic
Performance
- Jediah W. White
This study examined the effects of
explanatory style on athletic performance. The Attributional Style
Questionnaire was used to determine explanatory style for 188 college athletes.
In Experiment 1, athletes completed a sport-relevant physical task, received
false negative feedback, and completed the task a second time. I found that
pessimists performed significantly more poorly after negative feedback than
optimists. Experiment 2 divided 29 of the most pessimistic athletes into 2
programs. The experimental group received a six-session cognitive-behavioral
intervention designed to transform them into optimists. The control group
received a six-session discussion program that did not include optimism
training. Upon completion of the programs, these athletes participated in
Experiment 1. The cognitive-behavioral intervention significantly changed the
explanatory style of the pessimistic athletes and resulted in improved athletic
performance after negative feedback. The implications for sports performance
and explanatory style intervention are discussed.